With the rapid development of the electronics, more and more integrated circuits (ICs) are applied to a variety of communication and electronic devices. The ICs integrate active components such as transistors, diodes etc. and passive components such as resistors, capacitors etc. on a wafer through certain circuit interconnections. IC wafers can use a P-type doping substrate (P-sub), which is generally connected to a power ground (grounded) by default.
When an input voltage of the IC is a negative voltage, −6 volts (V) for example, a P-sub in a wafer of the IC can be grounded and the voltage coupled to a N-well can the input voltage, a forward bias voltage of 6V, for example, can occur at a PN junction in the IC, e.g., between the P-sub and the Nwell, leading to a large current passing through the PN junction and possibly damaging or burning out the IC.